Chronic Hip Flexor Problems in Hockey Players: Just the Tip of the Iceberg?

Hockey players are known for having chronic hip flexor issues. A lot of players will either complain of tight hip flexors or will have issues with constantly “tweaking” their hip flexors when skating volume increases. These are also usually the players who often complain of tight hips but yet are constantly stretching their hips. Before we chalk this problem up to weak or short hip flexors, I think we have to dig deeper into the anatomy and the research to get the whole picture and not just what’s at the surface.

Layers of the Hip

A good understanding of the anatomy will show that there’s much more to the hip than just bone and muscle. Previous research has described the hip in layers:

• Layer 1 – Bone shape and alignment
• Layer 2 – Passive stabilizers (ie ligaments, capsule, labrum)
• Layer 3 – Dynamic stabilizers (muscles)
• Layer 4 – Neuromechanical Control (muscle coordination)
• Layer 5 – Kinetic Chain (LSpine, pelvis, knee, ankle, etc.)

All of these structures combined work to stabilize the joint, create movement and dissipate forces. In symptomatic patients with these pathologies, they will often have pain and discomfort in the anterior hip/groin, which leads me to believe that chronic “tweaking” and/or tightness of the hip flexors might be more than just a muscle issue. Although it could feel like a strain on the surface, and there could be some secondary muscle irritation, there is likely a deeper underlying issue to the pain, discomfort and tightness.

By analyzing the skating stride, we can see how these structures could be irritated and damaged. At the end of push off, the leg is abducted, externally rotated and extended. External rotation torque in a position of abduction has shown to put high amounts of stress on the anterior labrum as the femoral head slides forward, shearing the labrum from the acetabular rim. Every stride adds to the cumulative strain, eventually leading to microtrauma, tearing and irritation of the labral tissue. With the high number of nociceptive fibers in the labrum, it can become a painful structure leading to muscle guarding from the hip flexor.

Additionally, the iliofemoral ligament is a main stabilizer of the anterior hip, restricting the femoral head from sliding forward in the joint. In the same position of abduction, ER and extension, the ligament is being stretched. Repeated stretching of the ligament through repetitive skating strides would decrease the viscoelastic properties of the ligament. In turn, leading to laxity of the ligament, greater femoral head translation and greater shearing on the labrum.

We also know that in ranges of hip abduction, there is increased strain on the anterior labrum. In the skating stride, players will get into between 25-40deg of hip abduction. Research on cadavers has shown that stress in the anterior labrum begins to increase exponentially from neutral to full abduction. So not only are we getting repeated shearing and microtrauma of the labrum from the sliding of the femoral head, but also from the ranges of abduction achieved in skating.

How to differentiate hip flexor from deeper problems

So then the big question becomes: How do you know if it’s just the hip flexor or if it’s something deeper? I think we have to be more specific to the common stressors of the sport with some of our provocative tests. If we are replicating the stress of the sport, there’s a better chance we can reproduce their pain and come up with a more accurate diagnosis.

Here is a cluster of provocative tests that can specifically stress the tissues of the anterior hip in positions similar to the skating stride. These tests put patients in positions of abduction, extension and external rotation with added anterior femoral head glides to recreate the strain from the abduction, extension and external rotation produced in the skating stride.

Abduction-Hyperextension-External Rotation

Prone Instability Test

Hyperextension-External Rotation Test

Now there’s no doubt that hockey players are at a higher risk of true hip flexor and adductors soft tissue injuries from the high velocity eccentric forces during push-off, but that may just be the tip of the iceberg.

References

Dy, C. J., Thompson, M. T., Crawford, M. J., Alexander, J. W., McCarthy, J. C., & Noble, P. C. (2008). Tensile strain in the anterior part of the acetabular labrum during provocative maneuvering of the normal hip. JBJS, 90(7), 1464-1472.

Hoppe, D. J., Truntzer, J. N., Shapiro, L. M., Abrams, G. D., & Safran, M. R. (2017). Diagnostic accuracy of 3 physical examination tests in the assessment of hip microinstability. Orthopaedic Journal of Sports Medicine, 5(11), 2325967117740121.

Myers, C. A., Register, B. C., Lertwanich, P., Ejnisman, L., Pennington, W. W., Giphart, J. E., … & Philippon, M. J. (2011). Role of the acetabular labrum and the iliofemoral ligament in hip stability: an in vitro biplane fluoroscopy study. The American journal of sports medicine, 39(1_suppl), 85-91.

Nho, S. J., Leunig, M., Larson, C. M., Bedi, A., & Kelly, B. T. (Eds.). (2015). Hip arthroscopy and hip joint preservation surgery. Springer New York.

Ollivier, M., Le Corroller, T., Parratte, S., Chabrand, P., Argenson, J. N., & Gagey, O. (2017). Mechanical strains passing through the acetabular labrum modify its shape during hip motion: an anatomical study. Knee Surgery, Sports Traumatology, Arthroscopy, 25(6), 1967-1974.